Aerial photo taken on May 26, 2022 shows a salt cavern compressed air energy storage facility in Changzhou City, east China's Jiangsu Province. [Photo/Xinhua]

China's first salt cavern compressed air energy storage facility, located in the city of Changzhou in east China's Jiangsu Province, started its expansion on Wednesday, said China Huaneng Group Co., Ltd.

Touted as the world's largest of its kind, the phase II project is expected to enable the power station to achieve the largest capacity globally and the highest level of power generation efficiency.

The expansion project aims to build two 350 MW non-combustion compressed air energy storage units, with a total volume of 1.2 million cubic meters.

Once completed, the facility will be able to store 2.8 million kWh of electricity on a single charge, which can meet the charging needs of 100,000 new energy vehicles. By then, the station is expected to help save 270,000 tonnes of standard coal and reduce carbon dioxide emissions by 520,000 tonnes annually.

The power station uses electric energy to compress air into an underground salt cavern, then releases air to drive an air turbine, which can generate electricity when needed. The salt cavern was formed following the exploitation of the underground salt layer in the area. At about 1,000 meters below ground, the salt cavern has a storage room equal in size to 105 swimming pools.

The energy storage project was co-developed by China National Salt Industry Group Co., Ltd., China Huaneng Group and Tsinghua University.